The best most effective way to migrate Mac OLM files to a number of email clients is to use the Data Recovery Freeware OLM file converter. This OLM file converter allows its users to convert OLM files into multiple file formats like PST, PDF, DOC, DOCX, etc. It also migrates the OLM file to a number of the email clients like Office 365, Thunderbird, Yahoo mail, Gmail, etc. However, this tool maintains the data hierarchy throughout the conversion process. However, it also automatically removes the OLM file on the basis of subject, from, to, body, etc. 

Professional Steps to convert OLM file

- Install the OLM file converter and run it as an administrator.

- Then select the OLM file to convert and click on the next button.

- Now select the OLM file to preview and click on the next button.

- After that select the file format to convert and set the path to the save button.

- Lastly, click on the convert button to start the conversion process

There are many other methods to convert OLM files if you want to know about the free methods then read this article 2 Free ways to convert OLM to PST for Outlook in easy steps.